1. Field of the Invention
The invention is based on a drum coater and a mixing tool.
2. Description of the Related Art
Drum coaters and mixing tools installed therein have been known from the prior art for a long time. Drum coating is the oldest method for coating and finishing active pharmaceutical ingredients and therefore a true classic. In drum coaters, bulk-like materials such as, in particular, tablets, capsules or very large pellets are coated with a surface layer, preferably sugar coatings, paints or even active ingredients. For this purpose, the bulk-like materials are simultaneously sprayed, preferably with a solution or suspension, and dried with a gas, particularly heated air. The bulk-like materials are sprayed in order to produce a surface layer, wherein this surface layer decisively influences the release of active ingredients. The coating furthermore makes it easier for the patient to ingest the products and even an unpleasant taste of the active ingredient can be masked with the coating. Simultaneous drying is required in order to evaporate the solvent from the sprayed-on solution or suspension and thereby produce the desired surface layer on the bulk-like material. Since the bulk-like materials in the drum of the drum coater should be coated with the desired film as uniformly as possible, it is vital to arrange mixing tools such as, for example, paddles or the like in the drum. Due to the design and arrangement of the mixing tools in a drum coater, the bulk-like materials are subjected to increased stress that, if applicable, can lead to partial damage or destruction of the bulk-like material.
Utility model DE 20 2009 017 787 U1 discloses a device for applying a surface layer on cores with a rotatably mounted drum for accommodating the cores, wherein the drum is realized in the form of an elongate cylinder that is larger than the diameter of the drum and has at least one spray nozzles for applying the surface material on the cores, a heating device for the interior of the drum, an inlet opening and an outlet opening, as well as driving elements for the cores that are arranged in the drum and connected to the drum, wherein the driving elements are realized in the form of projections that extend in the longitudinal axis of the drum and protrude into the drum interior. The disadvantages of this device can be seen in that no adequate blending of the cores by the driving elements is ensured in the drum of the device and that the driving elements subject the cores to high mechanical stress, e.g., in the form of friction or the like.
European patent EP 1 050 337 B1 describes a drum coater with forced recirculation of the product, wherein the drum for accommodating the product is rotatably mounted and provided with at least one spray nozzle for applying the surface material on the product, a heating device for drying the product, as well as first and second driving elements, wherein the second driving elements are arranged radially offset to the first driving elements. In this case, the second driving elements transport the product opposite to the first driving elements. The disadvantage of this technical solution can be seen in that the first and second driving elements subject the treated product to be blended to significant mechanical stress, which can lead to damage or even destruction of the product and thereby render the batch being treated in the drum coater unusable.